Abstract: Autistic Spectrum Disorders are diagnosed partly on the basis of impairments in social cognition. However, understanding the exact nature of these deficits has been difficult because there is no characterization of the nature of social inferences in typical development. In this talk I will present a theory of social cognition that posits a naïve utility calculus as the engine for making sense of the social world. I will show that even young children rely on this naïve utility calculus when they interpret other people’s actions, when they make moral evaluations, and when they interpret what other people say. Next, I will present a formal computational model that predicts with quantitative accuracy how neurotypical adults reason about simple social events, and I will show how, by using this model, we can uncover fine-grained similarities and differences in autistic adults.